Rover team members Kim Lichtenberg (left) and Mike Seibert fill a mixer with powdered clay and diatomaceous earth, a combination found to offer physical properties similar to the soil where NASA's rover Spirit is embedded on Mars.

Rover team members Kim Lichtenberg (left) and Mike Seibert fill a mixer with powdered clay and diatomaceous earth, a combination found to offer physical properties similar to the soil where NASA's Mars Exploration Rover Spirit is embedded on Mars. The team finished mixing the test soil and preparing a sloped testing area on June 29, 2009, with plans for driving the test rover into it on June 30.

To see updates on the efforts to free the Spirit rover, visit the JPL Free Spirit website.

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